Science News

The Bat Bunker

October 2, 2012

by Zuberoa Marcos

(Scroll down for Spanish version)

White-nose syndrome has killed millions of North American bats. Now a team of U.S. scientists at The Nature Conservancy has built the first artificial cave in Tennessee to save them. The cave will open to the bats this fall.

About 5.7 million bats have already succumbed to white-nose disease in the US, according to the best estimates from state and federal wildlife officials. Originated by the aggressiveGeomyces destructans fungus, it damages the bats’ wings and causes them to wake up when they should be hibernating. This burns their fat reserves too early, and the animals either starve to death or try to leave their caves in the dead of winter in search of food, often dying of exposure.

To date, there is no known treatment and the bats’ drastic decline has broad implications: the animals eat their weight in mosquitoes and other insects each day. By some estimates, they save American agriculture $3.7 billion annually.

The Nature Conservancy’s new hibernaculum hopes to protect bat populations. Made out of pre-cast concrete modules, it lies more than a meter below ground, stretches 24 meters in length, and could easily accommodate 200,000 bats.

To adapt to bats’ requirements, the cave was engineered to draw a continual supply of winter air from a concrete shaft to provide the chilly temperatures preferred by hibernating bats. The ceiling is scored with ridges and rough edges to give bat claws a tight grip. A rainwater pipe will bring in moisture to maintain the cave’s humidity levels and provide drinking water, and an air chimney will provide ventilation. Two 1.5-ton air conditioning units will run for the next few weeks to drop the cave’s temperature to the required range, between 41°F and 50°F.

The artificial cave won’t keep out the white nose fungus, but each autumn and spring, scientists plan to scrub it out with ammonia to keep it clean. Such a sanitizing procedure can’t be used in a natural cave environment because it would kill everything else and be detrimental to the ecosystem.

If the bat cave works, it will provide a new rescue plan for other endangered species. But there are no guarantees the bats will come in and use the artificial space. If they do, three surveillance cameras with infrared imaging will allow researchers to monitor bat movements without disturbing them. If they don’t, The Nature Conservancy’s experts can still use the cave as a field laboratory. They might bring some bats into the cave for testing new fungicides.

Zuberoa Marcos is a former biologist and current science writer based in Barcelona. She writes articles regularly for Science Today.

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